Hatnotes are short notes placed at the top of an article (hence the name "hat"). Hatnotes help readers locate a different article they might be seeking. Readers may have arrived at the article containing the hatnote because they were redirected, because the sought article uses a more specific, disambiguated title, or because the sought article and the article with the hatnote have similar names. Hatnotes provide links to the possibly sought article or to a disambiguation page.

In most cases, hatnotes should be created using a standard disambiguation template (as illustrated below). This permits the form and structure of hatnotes to be changed uniformly across the encyclopedia as needed.

Current Wikipedia style is to italicize and indent each note, without a bullet before the item. A horizontal dividing line should not be placed under a note, nor after the final item in a list.

Some hatnote disambiguation templates include a brief summary of the present article's topic; others do not. For instance, in the article Honey, one might use the template {{about|the insect-produced fluid}} to produce:

Either of these two styles is acceptable. The choice of style in a given article is based on editors' preference, and what is likely to be clearer and easier for the reader. Where an article already has a hatnote in one of these styles, editors should not change it to the other style without good reason or broad consensus.

Hatnotes are placed at the very top of the article, before any other items such as images, navigational templates and maintenance templates (like the "cleanup", "unreferenced", and "POV" templates). Text-only browsers and screen readers present the page sequentially. If a reader has reached the wrong page, they typically want to know that first.

When two articles share the same title, except that one is disambiguated and the other not, the undisambiguated article should include a hatnote with a link to the other article. It is not necessary to create a separate disambiguation page. {{about}} may be used for this. In this case the parameterization was {{about|the village in England|H. P. Lovecraft's fictional town|Dunwich (Lovecraft)}}.

This is a typical and highly improper misuse of disambiguating hatnotes. Instead, the information belongs in the body of the article, or in the articles about the book, or in a separate article about names, or all three places. Hatnotes are meant to reduce confusion and direct readers to another article they might have been looking for, not for information about the subject of the article itself.

Extraterrestrial life is life that may exist and originate outside the planet Earth. Its existence is currently hypothetical: there is as yet no evidence of extraterrestrial life that has been widely accepted by scientists...

Here, the hatnote is inappropriate because a reader who is following links within Wikipedia or using Wikipedia's own search engine would not have ended up at tree (set theory) if one were looking for other types of trees, since tree does not redirect there.

The use of external help links in Wikipedia, though noble, cannot reasonably be maintained. In special cases, a link to an "External links" section with several links may be appropriate, but POV favoritism can be obstructive. In this case, the hatnote was removed entirely.

Hatnotes should not be used for articles that do not exist since the notes are intended to point the user to another article they may have intended to find. The exception is if one intends to create the linked article immediately. In that case, consider creating the new article first, before saving the addition of the hatnote.